We incubated two highly weathered soils from the humid coastal region of Brazil, using lime at 1.5 times the exchangeable acidity and with 400 μMg.g−1of phosphate. The effects of these treatments on the soils' variable charges and on the leaching of added potassium chloride and soil cations from soil columns of reconstituted A and B horizons were evaluated. Both liming and ammonium phosphate treatments resulted in neutralization of exchangeable acidity and creation of new negative charges. Treatment effects were additive in only one soil. Increases in negative charge were attributed to pH increases and the unblocking of Al-hydroxide-occupied exchange sites. Significant amounts of native and applied K were leached, and leaching was not reduced by new charges from liming or P addition. Both applied Ca and P were leached in significant amounts to below the B horizon.